X-ray system with scanning beam x-ray source below object table

ABSTRACT

An x-ray system comprising a scanning beam x-ray source configured to projected at least one x-ray beam in a generally upward direction. When the generated x-rays are scattered they are scattered in a direction predominantly away from x-ray sensitive areas of attending staff. The unscattered x-rays are subsequently received at a detector and an image is reconstructed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to the field of x-ray imaging systems,including among other things, diagnostic x-ray imaging systems.

2. Background

Real-time x-ray imaging is increasingly being utilized by medicalprocedures as therapeutic technologies advance. For example, manyelectro-physiologic cardiac procedures, peripheral vascular procedures,PTCA procedures (percutaneous transluminal catheter angioplasty),urological procedures, and orthopedic procedures benefit from the use ofreal-time x-ray imaging.

A number of real-time x-ray imaging systems are known. These includefluoroscope-based systems where x-rays are projected into an object tobe imaged and shadows caused by relatively x-ray opaque matter withinthe object are detected on the fluoroscope located on the opposite sideof the object from the x-ray source.

Reverse-geometry x-ray imaging systems are also known. In such systems,an x-ray tube is employed to generate x-ray radiation. Within the x-raytube, high-energy charged particles are generated and focused on a smallspot on the relatively large target of the tube, inducing x-rayradiation emission from that spot. The charged particles are deflected(electromagnetically or electrostatically) in a raster scan pattern orotherwise over the target. A small x-ray detector is placed at adistance from the target of the x-ray tube. The detector typicallyconverts x-rays that strike it into an electrical signal in proportionto the detected x-ray intensity.

In known embodiments of reverse geometry diagnostic x-ray imaging systemthe x-ray source is located above the patient. When these x-ray imagingsystems are activated radiation is projected from the x-ray scanningtube, in a generally downward direction. As such, the radiation scatteroff of the patient and the x-ray table supporting the patient isgenerally in an upward direction. Since the scattered radiation isdirected predominantly in an upward direction, the attending staff oftenabsorbs the radiation in the most sensitive portions of the body, namelythe head and neck. Furthermore, since patients usually lie face up onthe x-ray table, when a woman is imaged, her breast tissue, which ismore sensitive than other tissue types, is subjected to the directradiation from the x-ray source.

Thus, there is a need for an x-ray imaging system that minimize x-rayabsorption risks to the patient and the attendant staff.

SUMMARY OF THE INVENTION

The present invention comprises an x-ray imaging system wherein thex-ray source is oriented such that extraneous x-rays scatterpredominantly in a direction away from the attending staff's x-raysensitive areas. According to a preferred embodiment of the invention,the x-ray system comprises an x-ray source and a detector, the x-raysource configured to project x-rays in a generally upward direction.

The invention also comprises the method of generating an x-ray imagewherein the extraneous x-rays are scattered predominantly in a directionaway from the x-ray sensitive areas of the attending staff. According toan embodiment, the method comprises the acts of projecting a pluralityof x-rays from an x-ray source, passing a first portion of the x-raysthrough an object table and toward an object to be imaged, scattering asecond portion of the x-rays off the object table, and away fromattending staff, and detecting the first portion of x-rays at adetector.

These and other objects, advantages, and aspects of the presentinvention will become apparent to those of ordinary skill in the artfrom a consideration of the drawings, description, and claims of theinvention contained herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention are illustrated by way ofexample, and not by way of limitation, in the figures of theaccompanying drawings and in which, like reference numerals refer tosimilar elements and in which:

FIG. 1 is a block diagram showing the basic components of an x-rayimaging system;

FIG. 2 is a side-view of a preferred x-ray imaging system;

FIG. 3A is a perspective view of a preferred x-ray imaging system shownrotated according to one embodiment;

FIG. 3B is a perspective view of a rotator mechanism according to oneembodiment of a preferred x-ray imaging system oriented for ease indescription;

FIG. 3C is a perspective view of an angulation mechanism according toone embodiment of a preferred x-ray imaging system;

FIG. 3D is a perspective view of a preferred x-ray imaging system with agantry shown rotated not more than 45° from vertical according to oneembodiment;

FIG. 4 is a perspective view of a preferred high-voltage vessel;

FIG. 5 is an exploded view of a preferred high-voltage vessel withcomponents associated therewith;

FIG. 6 is an exploded view of a preferred charged particle gunelectronics;

FIG. 7 is a second exploded view of a preferred high-voltage vessel withcomponents associated therewith;

FIG. 8 is an exploded view of a preferred x-ray source;

FIG. 9 is a perspective view of the x-ray source of FIG. 8 mounted on agantry;

FIG. 10 is a block diagram of a preferred imaging system;

FIG. 11 is a side elevation view of FIG. 4, parallel to a projectionaxis; and

FIG. 12 is a perspective view of an x-ray source emitting radiation witha portion of said radiation scattering according to one embodiment of apreferred x-ray imaging system.

DETAILED DESCRIPTION

FIG. 1 depicts the basic components of a reverse geometry x-ray imagingsystem. The x-ray source 100 preferably comprises an x-ray tube and ahigh-voltage charged particle source. The high-voltage charged particlesource is preferably connected to an adjustable high-voltage powersupply capable of generating approximately −70 kV to −120kV.

According to a preferred embodiment, the high-voltage power supplyprovides a DC output to the x-ray imaging system. At this voltage level,x-ray source 100 produces a spectrum of x-rays ranging to 120 keV. X-raysource 100 is an example of a scanning beam x-ray source in whichcharged particles are scanned across a target assembly. X-ray source 100includes deflection coils 104 under the control of a scan generator 108.High-energy charged particles 112 generated within vacuum chamber 158 bygun 111 are scanned across a target 120 preferably in a predeterminedstepping pattern. For example, the predetermined stepping pattern may bea raster scan pattern, a serpentine (or “S” shaped) pattern, a spiralpattern, a random pattern, or such other pattern as may be useful to thetask at hand. An apparatus that can be used in an embodiment of theinvention for generating and moving charged particles across target 120is disclosed in commonly owned U.S. Pat. No. 5,644,612, which isincorporated herein by reference in its entirety.

Charged particles 112 pass through vacuum chamber 158 and strike target120 at focal spot 124. X-rays 128 are emitted in all directions(although the term “x-rays” are used herein, it is for illustrationpurposes only—other forms of radiation can be employed according to thepresent invention.) For simplicity only a portion of the x-rays 128 areshown. To optimize system performance of a presently preferredembodiment, a x-rays are generated that diverge in a manner that justcovers the detector 136. This is preferably accomplished by placing acollimating element between the target 120 of the x-ray source 100 andthe detector 136, and more preferably between object 132 and x-raysource 100. According to one embodiment, the x-rays 148, after passingthrough collimation grid 144, only diverge slightly from axis 150.

The presently preferred configuration for the collimating element is agrid of x-ray transmissive conical apertures 140. Collimation grid 144is designed to permit passage to only those x-rays whose axes are in apath (e.g. axis 150) that directly intersects the detector 136.Collimation grid 144 preferably does not move with respect to thedetector 136 while the system is in operation. Thus, as chargedparticles 112 are scanned across target 120, at any given moment thereis only a single beam of x-rays 148 which pass through object 132 todetector 136. According to one embodiment, detector 136 has a facehaving an active area, wherein the area is broken into individualsegments 160. Each segment is a detector which, when combined, form adetector array, simply referred to as detector 136. A collimation grid144, useful in an embodiment of the invention, is disclosed in commonlyowned U.S. Pat. No. 5,859,893, which is incorporated herein by referencein its entirety.

The output of detector 136 is processed by an image reconstructionsystem 156 and displayed by a video display device 154 which ispreferably attached to a workstation 152. The video display device 154allows attending staff to view the x-ray images.

FIG. 10 depicts a block diagram of an embodiment of the imagereconstruction system 156. The image reconstruction system 156 comprisesa PCI interface 1010, which connects to control workstation 152. Adetection module 1020 comprises the components of detector 136 andreceives x-ray transmissiveness information. Image reconstructionchassis 1005 comprises an interface module 1030, one or more planereconstruction modules 1040, an image selection module 1050 and an imagepreprocessor 1060. The various components on the image reconstructionchassis 1005 are interconnected via one or more busses 1100, which alsoinclude control lines. PCI interface 1010 and detection module 1020 arecoupled to interface module 1030, whereas image preprocessor 1060 iscoupled to video post processor 1070. Video post processor 1070 iscoupled to display monitors 1080.

Details of the preferred embodiments of the components depicted withreference to FIG. 10 are described in detail in copending U.S. patentapplication Ser. Nos. 09/167,318, 09/167,397, 09/167,171 and,09/167,413, filed on the same day herewith, all of which areincorporated herein by reference in their entirety.

According to an embodiment, information about the x-rays 148 detected atthe detector 136 is fed back to scan generator 108. Accordingly, theworkstation 152 and the scan generator 108 are coupled.

Details of preferred elements depicted in FIG. 1, as well as elementsrelated to the same, are described in further detail in copending U.S.patent application Ser. Nos. 09/167,399, 09/167,523, and 09/167,639,filed on the same day herewith, all of which are incorporated herein byreference in their entirety.

FIG. 2 is a side view of a preferred x-ray imaging system 200. X-rayimaging system 200 comprises an x-ray source 204 connected to one end ofa curved gantry 208. At a second end of curved gantry 208 is attached adetector 212. According to one embodiment, the curved gantry 208 isattached to a base support 216. The gantry 208 is preferably capable ofmovement of a generally spherical rotation.

An x-ray table 220 (also referred to as an “object table”), preferablyhaving one or more x-ray transparent areas, supports an object for whichan x-ray image is desired. According to an embodiment of the x-ray table220, the x-ray table 220 can be a substantially flat table, having nodips or valleys. However, according to another embodiment it may includeone or more dips or valleys so as to more approximately curve to theshape of the object to be imaged. The x-ray source 204, is preferablylocated at the end of the gantry that is capable of movement in thelower hemisphere.

According to one embodiment, cabinet 218 supports a control workstationand display device (e.g., control workstation 152 and monitor 154).

When the system is operated, the electron gun generates a chargedparticle beam which strikes the target and generates x-ray photons. Thex-ray photons preferably pass through a collimator forming an x-raybeam. The x-ray beam has an axis that is preferably substantiallyaligned with the center of the active area of x-ray detector. The x-raybeam has a beam vector 205 which is defined by the x-ray beam axis inthe direction of the x-ray detector assembly as shown in FIG. 2. Themajority of the x-ray photons in the x-ray beam first pass through thetable 220 and the object under investigation before striking the x-raydetector.

FIGS. 3A-C depict, in greater detail, embodiments of mechanisms thatfacilitate the spherical motion of the gantry 208.

In FIG. 3A, gantry 208 is depicted rotated about a rotational pivot axis304. The rotation angle depicted in FIG. 3A is only illustrative of thedegree of rotation of the gantry 208. However, according to anembodiment, the gantry is configured to rotate to approximately 45° ofvertically upward direction, as depicted in FIG. 3D. Rotator mechanism308, depicted in further detail in FIG. 3B and described below, supportsgantry 208 and provides a force to drive gantry 208 about axis 304. Inaddition, a hydraulic support arm 312 further supports the load androtation of gantry 208 as it is rotated about axis 304 by rotatormechanism 308.

According to a preferred embodiment, gantry 208 is further configured toslide along a curved path concentric with a curve following the shape ofgantry 208. System axis 316, formed between x-ray source 204 anddetector 212, and pivot axis 304 intersect at point 324. Angulation axis320 is perpendicular to system axis 316 and pivot axis 304. Angulationmechanism 328 provides support and force to slide gantry 208 such thatgantry 208 slides in a circular or curved path about angulation axis320. According to one embodiment, angulation mechanism 328 comprisesbearing rails 332 and two drive belts 336. According to one embodiment,the bearing rails 332 also provide support for gantry 208. System vector317 is defined by system axis 316 in the direction of the x-ray detector212.

An enlarged view of the circled area 330 of angulation mechanism 328 isdepicted in FIG. 3C. Angulation mechanism 328 farther comprises anelectro-mechanical actuator 340 and belt drives 344. Electro-mechanicalactuator 340 rotates a drive wheel 348. Drive wheel 348 is connected viathe belt drives 344 to roller 352 around which drive belts 336 areconnected with tension. A control signal (not shown) is received byangulation mechanism 328 which, in turn, causes actuator 340 to begin torotate drive wheel 348 and consequently drive belts 336 begin to move.As drive belts 336 move, they carry gantry 208 along the path formed bybearing rails 332, or in other words, in a curved path about angulationaxis 320.

Turning to FIG. 3B, it depicts in further detail rotation mechanism 308.Rotation mechanism 308 is connected to gantry 208 via a rotationalsupport member 356 (FIG. 3A) that is connected to bearing rails 332(FIG. 3A). The rotational support member 356 provides not onlystructural support between the gantry and base support 216, but also, inconjunction with a hydraulic support arm 312, rotational assistance torotation mechanism 308. An electro-mechanical rotator actuator 360provides force to rotate gantry 208 about rotational pivot axis 304. Asthe rotator actuator 360 is actuated, internal gears (not shown) withinthe actuator 360 turn. While the internal gears turn, teeth 368 onrotational drive gear 364 engage the internal gears of the actuator 360and rotate rotational drive gear 364 about axis 304. Rotational drivegear 364 is connected to gantry 208 through rotational support member356, so when rotational drive gear 364 turns so does gantry 208.

FIG. 4 depicts high-voltage vessel 400. High-voltage vessel 400 housescharged particle gun electronics (not shown) that is employed to controlthe charged particle gun (e.g., gun 111). Further, high-voltage vessel400 is also configured to receive a high-voltage power supply line (notshown), which operates at a voltage potential between −70 and −120 kV.According to a preferred embodiment, high-voltage vessel 400 is alsoconfigured to receive fiber optic control lines (not shown) that areused to control the charged particle gun electronics.

Because high-voltage vessel 400 receives a high-voltage power supplyline and the high-voltage vessel itself has a voltage potential atground, the interior surface of high-voltage vessel 400 is polished andfree from irregularities which may cause electrostatic discharge betweenthe high-voltage vessel 400 and any object within the high-voltagevessel 400 that is maintained at a high-voltage (e.g., gun electronics).Additionally, sharp edges on the interior surface of the high-voltagevessel 400 are preferably chamfered or rounded to minimize electrostaticdischarge. To further protect against electrostatic discharge,high-voltage vessel 400 is sealably enclosed and designed to hold anon-conducting medium to prevent such electrostatic discharge. Accordingto a preferred embodiment, the non-conducting medium issulfur-hexafluoride (SF₆) gas. The SF₆ is preferably maintained inhigh-voltage vessel 400 at a pressure of 4 atm.

According to a preferred embodiment, high-voltage vessel 400 comprises acylindrical chamber 404, which is larger in diameter than in height. Thecylindrical chamber 404 has a chamber wall 408, an inner surface 412, anouter surface 416, a top surface 420 and a bottom surface 424. The topsurface 420 of cylindrical chamber 404 preferably is connected to awasher-shaped plate 428 that creates an inner lip and an outer lip 432,with reference to the chamber wall 408. Circumferentially arranged aboutthe outer lip 432 of plate 428 are a number of apertures 436 thoughwhich fasteners may pass. Additionally, along the inner mostcircumference of plate 428 is a mounting ring 440 comprising a number ofevenly distributed apertures 444. The apertures 444 are designed toreceive fasteners that will connect the high-voltage vessel 400 to thevacuum chamber (e.g., vacuum chamber 158).

The bottom surface 424 of cylindrical chamber 404 is preferablyconfigured to receive a chamber cover (not shown). A number of evenlydistributed cover apertures 448 are circumferentially arranged about thebottom surface 424 and allow the chamber cover to be sealably attachedto the cylindrical chamber 404. When attached to bottom surface 424 ofcylindrical chamber 404, the chamber cover is preferably flush with theinner surface 412 of the cylindrical chamber 404. Additionally,cylindrical chamber 404 preferably has smoothly chamfered interior edges452.

In the broader spirit of the invention, the high-voltage vessel 400 isnot limited to having a cylindrical chamber, such as cylindrical chamber404, rather, high-voltage vessel comprises any suitable chamberconfigured to house a gun electronics. In this regard, the high-voltagevessel 400 can comprise, for example, a hemispherical chamber or anelliptical chamber.

High-voltage vessel 400 preferably comprises a sleeve or tube 456,attached to the outer surface 416 of the chamber wall 408 and whichcreates an opening between the interior of the tube 456 and the innersurface 412 of cylindrical chamber 404. According to an embodiment, thetube 456 has an elliptical shape about a longitudinal axis and a slightelbow near one end.

In an embodiment, the tube 456 and the cylindrical chamber 404 arearranged such that the longitudinal axis of tube 456 form an angle φwith a plane that is perpendicular, or substantially perpendicular tothe longitudinal axis of cylindrical chamber 404. Angle φ is thesmallest angle formed by the intersection between the longitudinal axisof tube 456 and the plane perpendicular to the longitudinal axis ofcylindrical chamber 404. According to an embodiment, angle φ is lessthan 75 degrees, and in an alternate embodiment, angle φ is less than 30degrees.

In an alternate embodiment, the longitudinal axis of the tube 456preferably passes through the cylindrical chamber 404 to the innersurface 412 of chamber wall 408 such that the longitudinal axis of thetube 456 and the longitudinal axis of the cylindrical chamber 404 forman acute angle, as measured, generally, between the longitudinal axis ofthe tube 456 and a projection direction of a charged particle gun. Inanother embodiment the angle is substantially perpendicular, that isbetween approximately 60 and 120°. Finally, it should be noted that thelongitudinal axis of the tube 456 and the longitudinal axis of thecylindrical chamber 404 do not have to be coaxial.

At one end of tube 456 a number of fastener apertures 464 are disposedabout the outer edge 460. The fastener apertures 464 are configured toengage fasteners which secure a high-voltage feed through (not shown) tothe high-voltage vessel 400. High-voltage vessel 400 preferablycomprises a tube support 466 disposed between the outer lip 432 of thecylindrical chamber 404 and above the tube 456.

FIG. 5 is an exploded view of a high-voltage vessel 400 and thecomponents associated therewith. For example, high-voltage vessel 400houses charged particle gun electronics 504, which is connected to thecharged particle gun (not shown). A vessel cover 508 sealably enclosesgun electronics 504 within the cylindrical chamber 404.

High-voltage mount 512 attaches to tube 456 at end 460. According to oneembodiment, high-voltage mount 512 comprises a high-voltage receptacle524 having a feedthrough end 525, which preferably receives one end of a−120 kV power supply line 516, a fiber optic receptacle 520, whichpreferably receives fiber optic control lines, and a high-voltagefeedthrough 528, which shields the interior of tube 456 from the end ofhigh-voltage power supply line 516. A receptacle vector 527 is definedby the longitudinal axis of the high voltage receptacle 524 and thedirection of insertion of the high voltage cable 516 into the highvoltage receptacle 524. In a presently preferred embodiment, the anglebetween the system vector 317 and the receptacle vector 527 isapproximately an acute angle.

When enclosed, high-voltage vessel 400 preferably does not allow gas toflow from the interior of the high-voltage vessel 400 out andvise-versa. A sealant or gasket may be disposed between the cover 508and the bottom surface 424 of the cylindrical chamber 404, and the mount512 and the end 460 of the tube 456. Fiber optic receptacle 520 ispreferably sealed with or comprised of an epoxy resin, or an equivalentgasket.

FIG. 6 depicts an exploded view of gun electronics 504. According to oneembodiment, the gun electronics 504 comprises an end cap 608, a ringhousing 612 and a printed circuit board 620. The ring housing 612 mountsto the end cap 608. Disposed between the ring housing 612 and the endcap 608 is the printed circuit board 620. The printed circuit board 620has on it control electronics to control charged particle gun. Accordingto another embodiment, the gun electronics 504 further comprises amechanical ring housing 614 and, on top of the mechanical ring housing614, a second printed circuit board 618. The mechanical ring housing 614and the second printed circuit board 620 are disposed between the endplate 608 and the first printed circuit board 620. Further, a fiberoptic and power cable connector 628 is mounted to a side of mechanicalring housing 614, and an electronics cover 624 is connected to thebottom surface of ring housing 612. The electronics cover 624, the ringhousing 612 and the mechanical ring housing 614 each contain a number ofopenings 636 through which gas and heat may pass. Preferably, ifhigh-voltage vessel 400 is filled with SF₆ gas, then the gas freelyflows through the openings 636. In a preferred embodiment, a chargedparticle gun (not shown) is mounted to end plate 608 via a gun sleeve632. When the x-ray source is activated, the gun is capable ofprojecting charged particles along the longitudinal axis of the chargedparticle gun and towards the target (not shown) that is above the endplate 608.

FIG. 7 is a perspective exploded view that depicts the interconnectionsbetween high-voltage vessel 400 and its associated components. Accordingto an embodiment, once the high-voltage vessel 400 is assembled, twoconducting cables (not depicted in FIG. 7) run between the high-voltagereceptacle 528 and gun electronics 504 (FIG. 5). Since the gunelectronics 504 does not include a power transformer to power theelectronics circuits enclosed therein, power is provided by the twoconducting cables, which have a voltage differential of approximately 30V. The gun electronics 504 is maintained at approximately −100 kV duringoperation of the x-ray source. In addition to the two conducting cables,fiber optic cables (not shown) are also run between connector 628 andfiber optic cable receptacle 520.

FIG. 8 is an exploded view of a preferred embodiment of the x-ray source800.

According to the preferred embodiment, the x-ray source 800 comprises ahigh-voltage vessel 400, a charged particle gun, a first focus coil, asecond focus coil, deflection coils, a deflection insulator, a targetand a vacuum chamber. In one embodiment, the x-ray source is stacked,from the bottom up, such that the high-voltage vessel 400 receives anelectron gun 804. A first focus coil 808 is positioned above theelectron gun 804. A second focus coil 812 is mounted on top of the firstfocus coil 808. A deflection insulator 820 is received by openingswithin the first focus coil 808, the second focus coil 812 and thedeflection coils 816. The deflection insulator 820 is attached to theelectron gun 804. A vacuum chamber 822 is attached to an end of thedeflection insulator 820, and a target 826 is placed over the vacuumchamber 822. A cradle 828 wraps around approximately three-quarters ofthe x-ray source 800 and extends between the top surface of high-voltagevessel 400 and approximately midway along the vacuum chamber 822.Finally, the high-voltage power cable 516 is received by high-voltagevessel 400 at high-voltage receptacle 524.

The currents flowing within first focus coil 808 and second focus coil812 cause the charge particles 112 to be brought into focus at focalspot 124. Further, deflection coils 816 cause the charged particles 112to track a particular scan pattern across target 826.

FIG. 9 is a perspective view of the x-ray source 800 mounted at one endof gantry 208. According to a preferred embodiment, x-ray source 800 ismounted on the lower end of gantry 208. To provide further support tox-ray source 800 as it rests on one end of gantry 208, cradle 828 isattached to gantry 208 via support arms 904. Fiber optic communicationand control cables 908 are received into fiber optic cable receptacle520. Both the fiber optic cables 908 and the high-voltage power supplyline 516 are strung along the interior of gantry 208.

Referring to FIG. 11, according to an embodiment, the high voltage powersupply line 516 is recieved into a high-voltage receptacle 524 on highvoltage vessel 400 such that the longitudinal axis of the high-voltagerepresents 524, illustrated by receptacle vector 527, forms an angle θwith a projection plane 810 defined by the projection axis of thecharged particle gun. In an embodiment, the projection plane 810 isdefined as a plane perpendicular or substantially perpendicular to theprojection axis of the charged particle gun and angle θ is the smallestangle formed by the intersection of the longitudinal axis (receptablevector 527) of the high voltage receptacle 524 with the projection plane810. In one embodiment, angle θ is less than 75 degrees, and in anotherembodiment, angle θ is less than 30 degrees.

In an alternate embodiment, high voltage power supply line 516 (FIG. 9)is received into high-voltage receptacle 524 on high-voltage vessel 400such that the longitudinal axis (receptable vector 527) of thehigh-voltage receptacle 524 forms an acute angle with the projectionaxis 316 of the charged particle gun, as measured between thehigh-voltage receptacle 524 and the charged particle gun with referenceto the projection direction of the charged particle gun. Alternatively,the angle is substantially perpendicular, between approximately 60° and120°. Finally, it should be noted that the longitudinal axis (receptablevector 527) of the high-voltage 524 does not need to intersect theprojection axis of the charged particle gun.

According to an embodiment of the innovative configuration and assemblyof the x-ray system described herein, the x-ray source is compact enoughto fit below, rather than above, the patient and the x-ray table.Consequently, when the x-ray system is activated and radiation isemitted, the x-ray scatter is predominantly downward, rather thanupward, as depicted in FIG. 12 where a first portion of the emittedradiation passes through the x-ray table 220 and a second portion of theemitted radiation scatters off of the x-ray table 220 in a predominatelydownward direction. As a result, the risk of exposure to harmful x-raysis reduced to the attending staff, as well as depending on the procedurebeing performed, to the x-ray sensitive tissues of the patient.Additionally, the positioning of the x-ray source is highly adjustable,allowing movement in a spherical pattern about the x-ray table orpatient. For example, according to an embodiment, the x-ray source iscapable of movement about a target object such that the system axis canvary at least between 0° and 45° from a vertically upward direction. Inan embodiment, the system axis is the axis extending from the x-raysource to the detector.

In the foregoing specification, the invention has been described withreference to specific embodiments thereof. It will be evident, however,that various modifications and changes may be made thereto withoutdeparting from the broader spirit and scope of the invention. Thespecification and drawings are, accordingly, to be regarded in anillustrative, rather than a restrictive sense.

What is claimed is:
 1. An x-ray system comprising: a scanning beam x-raysource, said scanning beam x-ray source comprising a vacuum chamber, oneor more deflection coils, and a target comprising one or more focalspots, said scanning beam x-ray source configured to project x-rays inan upward direction, and said scanning beam x-ray source configured toscan said x-rays across an area of interest; and a detector, saiddetector arranged to receive at least a portion of said x-rays, and asystem axis extending from said scanning beam x-ray source to saiddetector, said system axis deviating not more than 45° from vertical. 2.The x-ray system of claim 1, wherein said scanning beam x-ray sourcefurther comprises: a charged particle gun, said charged particle gunhaving a projection axis and a projection plane perpendicular to saidprojection axis; a high voltage vessel comprising a high voltagereceptacle, said high voltage receptacle having a receptacle axis; andsaid charged particle gun and said high voltage vessel arranged suchthat said receptacle axis intersects said projection plane, wherein anangle of the intersection between said receptacle axis and saidprojection plane is less than 75°, said angle being the smallest angleformed by said intersection.
 3. The x-ray system of claim 2, whereinsaid angle is less than 30°.
 4. The x-ray system of claim 2, saidscanning beam x-ray source including two conducting cables disposedbetween said high-voltage power cable receptacle and said chargedparticle gun, said conducting cables configured to operate atapproximated −100 kV, and to provide a voltage differential ofapproximately 30 V to said charged particle gun.
 5. The x-ray system ofclaim 1, said scanning beam x-ray source further comprising: ahigh-voltage vessel, said high-voltage vessel having a high-voltagepower cable receptacle configured to receive a high-voltage power supplyalong a longitudinal axis of said high-voltage power cable receptaclesuch that said longitudinal axis of said high-voltage power cablereceptacle and said x-ray projection axis form an acute angle; and a gunelectronics housed within said high-voltage vessel.
 6. The x-ray systemof claim 5 wherein said x-ray projection axis and said longitudinal axisof said high-voltage power supply intersect.
 7. The x-ray system ofclaim 5, said high-voltage vessel comprising: a cylindrical chamberhaving a top surface, a bottom surface, an interior surface, an outersurface, a wall and an opening, said cylindrical chamber having a heightwhich is less than its diameter, and said cylindrical chamber configuredto house a gun electronics; and a tube having open ends, one end of saidtube attached to said outer surface of the chamber wall such that theinterior of said tube connects with the interior surface of saidcylindrical chamber, and said tube configured to hold said high-voltagepower cable receptacle.
 8. The x-ray system of claim 5, said scanningbeam x-ray source including two conducting cables disposed between saidhigh-voltage power cable receptacle and said gun electronics, saidconducting cables configured to operate at approximated −100 kV, and toprovide a voltage differential of approximately 30 V to said gunelectronics.
 9. The x-ray system of claim 1, further comprising a gantryhaving two ends, said gantry configured to support said detector andsaid scanning beam x-ray source each on an end, and said gantryconfigured to facilitate movement of said scanning beam x-ray source.10. The x-ray system of claim 9, further comprising: an angulationmechanism connected to said gantry, said angulation mechanism comprisingan actuator, said actuator configured to move gantry about an angulationaxis.
 11. The x-ray system of claim 9, further comprising a rotationmechanism connected to said gantry, said rotation mechanism configuredto cause said gantry to rotate about a radial axis.
 12. The x-ray systemof claim 1, said scanning beam x-ray source further comprising: ahigh-voltage vessel; and a high-voltage power cable receptacle connectedto said high-voltage vessel, said high-voltage power cable receptacleconfigured to receive a high-voltage power supply along a longitudinalaxis of said high-voltage power cable receptacle such that saidlongitudinal axis and said x-ray projection axis form an acute angle.13. The x-ray system of claim 1, said scanning beam x-ray source furthercomprising: a gun electronics coupled to said charged particle gun, saidgun electronics configured to receive power from a source other than atransformer; a high-voltage vessel, said high-voltage vessel housingsaid gun electronics, and said high-voltage vessel configured to receivea high-voltage power supply cable along a first axis such that saidfirst axis and said x-ray projection axis form an acute angle; a vacuumchamber, said vacuum chamber attached to said high-voltage vessel; afirst focus coil, said first focus coil mounted to said high-voltagevessel and surrounding a first portion of said vacuum chamber; a secondfocus coil, said second focus coil attached to said focus coil andsurrounding a second portion of said vacuum chamber; and a chargedparticle target, said charged particle target mounted to said vacuumchamber.
 14. The x-ray system of claim 1, further comprising an objecttable, said object table located approximately above said scanning beamx-ray source and below said detector.
 15. An x-ray system comprising: ascanning beam x-ray source, said scanning beam x-ray source generatingx-rays, said scanning beam x-ray source comprising a high-energyparticle generator, a vacuum chamber, one or more deflection coils, anda target comprising one or more focal spots, and said scanning beamx-ray source capable of scanning said x-rays across an area of interest;a detector, said detector arranged to receive at least a portion of saidx-rays; and an object table, said object table disposed above saidscanning beam x-ray source.
 16. An x-ray system comprising: a scanningbeam x-ray source, said scanning beam x-ray source comprising an x-rayprojection axis, a high-energy particle generator, a vacuum chamber, oneor more deflection coils, and a target comprising one or more focalspots, said x-ray projection axis being within 45° of a verticallyupward direction, and said scanning beam x-ray source capable ofscanning one or more x-ray beams across an area of interest; an objecttable, said object table located approximately above said scanning beamx-ray source; and a scanning beam x-ray source support structure, saidscanning beam x-ray source support structure configured to allowspherical movement of said scanning beam x-ray source about said objecttable.
 17. A method for generating an x-ray image comprising: projectinga plurality of x-rays from a scanning beam x-ray source, said scanningbeam x-ray source comprising a high-energy particle generator, a vacuumchamber, one or more deflection coils, and a target comprising one ormore focal spots; scanning said plurality of x-rays across an area ofinterest; passing a first portion of said plurality of x-rays through anx-ray table and toward a target body; scattering a second portion ofsaid plurality of x-rays off said x-ray table and away from attendingstaff, and detecting said first portion of said plurality of x-rays at adetector, said x-rays having passed through said x-ray table andsubsequently through said target body.